The present invention relates to photographic processing equipment. In particular, the present invention relates to an improved paper feed control system for use in an automatic photographic paper cutter.
In commercial photographic processing operations, very high rates of processing must be achieved and maintained in order to operate profitably. To expedite the photographic processing, orders containing film of similar type and size are spliced together for developing. As many as 500 to 1000 rolls of 12, 20, and 36 exposure film may be spliced together for processing and printing purposes.
After developing, the photographic images contained in the film negatives are printed in an edge-to-edge relationship on a continuous strip of photosensitive paper by a photographic printer. The photographic printer causes high intensity light to be passed through a negative and imaged on the photographic print paper. The photographic emulsion layer on the print paper is exposed and is subsequently processed to produce a print of the image contained in the negative.
After the strip of print paper has been photoprocessed to produce prints, a photographic paper cutter cuts individual prints from the strip. The prints are then sorted by customer order and ultimately packaged and sent to the customer.
Automatic print paper cutters have been developed which automatically cut the print paper into individual prints. These automatic paper cutters are controlled by indicia which are placed along the print paper by the photographic printer. Typically the indicia are of two types: cut marks and end-of-order marks. The cut marks indicate the desired location of a cut between adjacent prints. The end-of-order marks, which typically appear along the opposite edge of the print paper from the cut marks, indicate the end of a customer's order. The automatic paper cutter includes a sensor which senses the cut mark and causes the individual prints to be cut from the strip at the desired locations. The separated prints are passed to an order packaging or grouping device, which groups the prints in response to the end-of-order marks which are sensed by the automatic cutter.
The desire for high rates of processing within commercial photographic processing operations has led to the development of extremely high speed automatic paper cutters. Automatic paper cutters capable of cutting over 25,000 prints per hour (i.e. over 7 prints per second) are needed, and are being developed.
One obstacle to achieving the desired high speed operation in automatic paper cutters is the problem of missing cut marks. While the photographic printers which produce the cut marks are generally very reliable, occasionally a cut mark is either not made or is made improperly so that the cut indicia sensor does not sense a cut mark. As a result, an incorrect paper feed is produced. The operator generally must stop the automatic paper cutter, or the automatic paper cutter may stop automatically if no cut mark is sensed.
While this problem is present with lower speed automatic paper cutters, it becomes particularly important when extremely high speed operation is desired. Any stopping of the paper cutter, even for one minute, significantly reduces the output of a high speed automatic paper cutter.